Testing Gauss-Bonnet gravity with x-ray binary observations

We examine the spacetime geometry of the spinning black hole in Gauss-Bonnet gravity as a model for the geometry around several x-ray binary black hole sources; A0620-00, H1743-322, XTE J1550-564, GRS1124-683, GRO J1655-40, and $\mathrm{GRS}1915+105$. This metric extends the Kerr solution by including a Gauss-Bonnet coupling parameter $\ensuremath{\alpha}$, capturing higher-curvature corrections. We first assess whether observed radiative efficiencies can be reproduced within this framework. We then analyze whether the spacetime geometry of the spinning black hole in Gauss-Bonnet gravity can also account for the observed jet powers. While most sources show consistent behavior across Lorentz factors $\mathrm{\ensuremath{\Gamma}}$, GRS1124-683 exhibits greater sensitivity. Combining both radiative and jet constraints, we identify overlapping parameter regions for A0620-00, H1743-322, GRO J1655-40, and XTE J1550-564. For GRS1124-683, overlap depends on the assumed $\mathrm{\ensuremath{\Gamma}}$, and for $\mathrm{GRS}1915+105$, no consistent region is found under current assumptions. Our results highlight both the potential and limitations of Gauss-Bonnet gravity in describing strong-field astrophysical systems.